Last Wednesday at breakfast, my generation discovered that our time is up. I got wind of the news on Tuesday by reading it online but, like most people my age, I never entirely believe something until I see it printed on a large sheet of paper, anachronistically delivered to my door by the paper boy. So for me, the penny did not drop until Wednesday morning that the world now belongs to the generation below mine.

At the bottom of the front page of the Financial Times it said that Facebook is now bigger than Google. In the US, more people now visit the social networking site to write on each other's walls and swap pictures of drunken japes at parties than turn to Google to get travel directions, check the spelling of “definitely” or search for internet porn.

Social networking, it seems to me, is the biggest separator of the young from the not-so-young. In most other respects there is not much to choose between people of 50 and of 15, apart from a bit of experience and a great many wrinkles. Everyone wears jeans. More or less everyone (quite) likes Florence and the Machine. But 15-year-olds live on Facebook, while 50-year-olds don't understand it at all.